1. Field of the Invention
This invention relates to a peak clipper for use in a pre-stage of the modulating circuit that amplitude-modulates a video signal.
2. Description of the Related Art
A peak clipper is used in the RF modulator built in a VCR (Video Cassette Recorder), for example. The RF modulator converts the processed signal in the VCR into a radio frequency (RF) suitable for television. The peak clipper prevents signals other than the specified video signal, such as noise, from entering the video signal modulating circuit in the RF modulator.
In the clipper circuit operation, it is important that variations in the video signal lower than the clipping level are transmitted to the next stage, maintaining the linear characteristics. Since most peak clippers simply make use of the switching operation at a differential transistor pair, the approach of the clipping level makes the clipping operation slower, worsening the linear characteristics. That is, gradual start of clipping at a voltage below the clipping level makes the linear region narrower. As a result, a signal of high luminance or large amplitude can enter the linearity-collapsed region near the clipping level, which distorts the video signal.